Media Chapter File Builder
Build WebVTT chapter cues or FFmetadata chapter blocks from explicit titles and integer millisecond boundaries.
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How to use Media Chapter File Builder
Create a reviewable chapter sidecar without sending or editing the media file. The declared duration closes the last chapter, source order is validated, and literal title characters are escaped for the chosen output profile.
- Enter input, total media duration in ms.
- Choose the settings for media chapter file builder, then run the tool.
- Review the result and any limitations before copying or downloading it.
Good to know
- 500 chapters, single-line titles up to 1,000 characters, 100,000 JSON characters and a declared duration up to 24 hours. Starts are unique increasing integer milliseconds.
- No media timing inspection, remuxing, language selection or guaranteed player compatibility. The downloaded file must be tested with its intended player or import workflow.
- Processing is local. Output is limited to 1,000,000 text characters unless a stricter file limit is stated.
Common questions
Does the first chapter have to start at zero?
No. A later first start is allowed, and the report explicitly records the uncovered beginning. All chapter ends are derived from the next start or total duration.
Is this input sent to a server?
No. The application processes this input inside your browser tab and does not save it to persistent storage.
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